Epidemiologic studies of occupational groups are conducted to identify and clarify the role of environmental factors in the origin of cancer. During the past year, several studies of workers exposed to formaldehyde were completed. A case-control study of nasal cancer in the Netherlands noted approximately a twofold risk among persons exposed to formaldehyde. A mortality study of anatomists uncovered a threefold excess of brain cancer (predominantly gliomas) and a slight excess of leukemia. A large study of industrial workers exposed to formaldehyde uncovered an excess mortality of lung cancer that did not increase with increasing level of exposure and an excess from cancer of the nasopharynx particularly among those exposed to particulates. Several reports were completed on cancer risks among farmers exposed to pesticides. A case-control study uncovered a striking dose-response between risk of non-Hodgkin's lymphoma and a number of days of use of the phenoxyacetic acid herbicide, 2,4-D. A mortality study of pottery workers identified an excess of lung cancer that was closely linked to exposure to talc in molding processes. An evaluation of time-trends of mesothelioma showed an increase in incidence that could not be accounted for by changes in diagnostic practices. Following a lead from a proportionate mortality study, a case-control study of bladder cancer detected an elevated risk for this cancer among artistic painters that increased with the number of years of artist painting activities. Important methodologic issues in occupational epidemiology were also addressed. For example, a manuscript was published describing procedures used to estimate historical levels of exposure to formaldehyde for a major cohort mortality study.